In my music tech course we are starting to study Binary and Hex, and although I understand the relationship, I wonder, how often do you experienced MIDI composers use either?
Probably never. It's used in part of the details of how the MIDI protocol is built. If you were writing code to interpret MIDI files or MIDI messages, then you would use that. But it's not something you would use at the user level.
But back on topic, Yes I have used Binary and hexadecimal on a few rare ocassions. (tracking down problem messages/notes in the midi events list) Its not hard stuff (but it is easy to mess up) so why not learn it just in case.